Sunday, September 7, 2014

A bit over a week ago, Zipp announced at Eurobike the release of their entirely new tire line; specifically, the Tangente Speed and Course clincher models (in 23C and 25C versions for both) along with the Tangente SLSpeed Tubular models (a 24C and a whopping 27C version). Below you'll find my roller testing results for these new tires. The Speed models are based on a 220tpi nylon casing and forgo an under the tread puncture belt, while the Course models use a 127tpi nylon casing and use puncture belt. The SLSpeed tubular models use a similar tread that is glued to a 320tpi cotton tubular casing with a latex tube inside and they also feature a puncture belt.

The previous Tangente models from Zipp were apparently very good from an aero standpoint. From a rolling resistance standpoint however, they were "less than stellar"...especially in this day of tire companies understanding the value of low Crr tires and their effect on performance and "comfort". So, one of the main drivers of this new tire development was in lowering the Crr of their tire offerings. On this point, I'd have to say that they've succeeded, in that Course models are basically tied with the current "industry standard" Continental GP4000S 23C from a Crr standpoint, with the Speed models being slightly faster. Their new tubular models, the Tangente SLSpeed, are also very low rolling resistance, with the 24C model basically tied with the benchmark Schwalbe IronMan Tubular, and the 27C (with the helping of its extra wide casing) taking over the current top spot for a "brand new" tire on the overall list of tires I've tested.

So, here's the nitty-gritty data for these tires, including data for the Schwalbe IM tubular, my "benchmark" GP4000S 23C tire, and the old model Tangente tubular. All of the clincher data for this round was performed on a Zipp Super 9 clincher disc, with the tubulars all tested on Zipp 900 tubular discs for consistency. In rank order from lowest Crr to highest:

So...what are the takeaways here? Well, I think it's fair to say that Zipp accomplished their goal of significantly improving the Crr of their tires, which can be easily seen by the comparison to the old Tangente tubular. Even the slowest of the new tires would save ~7W for a pair at 40kph, with the faster tires requiring more than 10W less at 40kph. That's significant. Also, in comparison to the GP4000S, the 25C Course model is basically tied with it, both in Crr and in actual tire width (at ~24.7mm) with the 23C Course model being only slightly slower (within the error margin of the testing). The 23C version of the Speed models tested out slightly faster than the GP4000S (again within the margin of error) but measures a full 1mm narrower when mounted on the same rim. That should help its aero properties. The 25C Speed model, however, is significantly lower Crr than the GP4000S saving a predicted 4W for a pair at 40kph, while measuring out at the identical width.

On the tubular front, the new 24C Tangente SLSpeed tire rolls just slightly better (within .0001 Crr) of the Schwalbe IronMan tubular, which is not surprising considering their similar construction (tread glued to a 320tpi cotton casing). The 27C Tangente SLSpeed tire rolls VERY fast, but its extra wide 26.8mm mounted width is going to result in an aero hit. I'd call that one a "rear use only"...but only as long as it can be shown that the width doesn't "give back" aerodynamically the gains that are made in Crr.

Well, that's the Crr results. What remains to be seen is how these tires perform aerodynamically. But, as I've said before, and we've seen recently with tires like the Specialized Turbo Cotton, low Crr can "make up for a lot of aerodynamic sins".